Shearing contact switch

ABSTRACT

A switch for closing an electrical circuit upon relative movement of a pair of members includes a hollow cylindrical tube mounted adjacent one end to one of the members. The other end of the tube is provided with a sharpened edge. A support member of shearable insulating material is mounted to the other member and includes a first cylindrical portion receiving and piloting the free end of the tube and a second adjacent cylindrical portion of larger diameter. In one embodiment, a second contact member includes a first cylindrical portion embedded within the first portion of the support member and a second larger cylindrical portion embedded within the second portion. Upon relative movement of the members, the sharpened edge of the tube shears off the outer layer of the second portion and engages the second portion of the second contact member to close a circuit across a source of power. In another embodiment, a rod extends through both portions of the support member and spaced contacts are embedded within the second portion in the path of movement of the tube for electrical contact thereby when the tube shears off the outer layer of the second portion of the support member.

United States Patent Maddy et al.

[54] SHEARING CONTACT SWITCH [72] Inventors: Sanford L. Maddy, Middletown; Jackson R. Templin, Anderson, both of Ind.

[73] Assignee: General Motors Corporation, Detroit,

Mich.

[22] Filed: Mar. 15, 1971 [21] Appl.No.: 124,324

Thomison ..200/61 .08

[ 5] Feb. 29,1972

Primary ExaminerRobert K. Schaefer Assistant Examiner-M. Ginsburg Attorney-W. E. Finken and Herbert Furman [5 7] ABSTRACT A switch for closing an electrical circuit upon relative movement of a pair of members includes a hollow cylindrical tube mounted adjacent one end to one of the members. The other end of the tube is provided with a sharpened edge. A support member of shearable insulating material is mounted to the other member and includes a first cylindrical portion receiving and piloting the free end of the tube and a second adjacent cylindrical portion of larger diameter. in one embodiment, a second contact member includes a first cylindrical portion embedded within the first portion of the support member and a second larger cylindrical portion embedded within the second portion. Upon relative movement of the members, the sharpened edge of the tube shears ofi the outer layer of the second portion and engages the second portion of the second contact member to close a circuit across a source of power. In another embodiment, a rod extends through both portions of the support member and spaced contacts are embedded within the second portion in the path of movement of the tube for electrical contact thereby when the tube shears off the outer layer of the second portion of the support member.

4 Claims, 2 Drawing Figures Patented Feb. 29, 1972 3,646,286

' INVENTORS Sara/$10 [f Win 5&6

A T TORNE Y SHEARING CONTACT SWITCH This invention relates generally to switches and more particularly to switches for closing an electrical circuit upon relative movement of a pair of relatively movable members.

One of the features of the switch of this invention is that relative movement of the members causes one of the switch contacts to shear off an insulating layer covering the other switch contact and electrically contact such other contact to close a circuit. Another feature is that the other contact is mounted within a contact support member which guides the movement of the one contact upon relative movement of the members. A further feature is that the support member for the other contact includes spaced cylindrical portions, one of which pilots and guides a cylindrical tube comprising the one contact and the other of which houses the other contact engaged by the tube when a sharpened free edge thereof shears off the outer layer of the second portion covering the second contact.

These and other features of the switch of this invention will be readily apparent from the following specification and drawings wherein:

FIG. 1 is a sectional view of a switch according to one embodiment of the invention; and

FIG. 2 is a sectional view of a switch according to another embodiment.

Referring now to FIG. 1 of the drawings, a switch designated generally according to one embodiment of the invention includes a cylindrical metal tube providing a first contact 12 having one end thereof secured in a suitable manner to a bracket 14 which is bolted at 16 to one member 18 of a pair of relatively movable members. The free end of the tube 12 is provided with a sharpened edge 20 for a purpose to be hereinafter described.

A contact support member 22 of shearable insulating material includes first and second cylindrical portions 24 and 26. A combined contact and reinforcement member 28 is embedded within the member 22 and includes a cylindrical portion 30 which provides a reinforcement for the portion 24. A cylindrical portion 32 is joined to the portion 30 by a radially and axially tapered shoulder 34 and provides both a second contact, as will be described, and a reinforcement for the portion 26. The OD of portion 32 is slightly larger than the ID of member 12. A conventional spade contact 36 is welded to the free end of the portion 32 and extends outwardly through the flanged base 38 of the member 22. Base 38 is bolted at 40 to a member 42 which is'the other of the pair of relatively movable members. The member 12 and the contact 36 are electrically connected across a source of power, such as the vehicle battery, not shown.

Normally the portion 24 pilots the free end of the member 12 to accurately locate the member with respect to the portion 32 ofmember 28.

Upon relative movement of the members 18 and 42 toward each other, the sharpened edge 20 of member 12 engages the portion 26 of member 22 and begins to shear off the outer layer of this portion. As soon as the member 12 contacts the portion 32 of member 28, the electrical circuit across the source of power is completed and whatever mechanism is to be actuated by the switch 10 is thereupon actuated. The switch 10 shown here has particular usefulness in,an occupant restraint system and may be mounted between a displaceable part of the body, such as the bumper, and the body structure so as to actuate electrically fired detonators which rupture a diaphragm of a sealed pressure vessel to release the fluid for inflation of the cushion upon displacement of the bumper and body relative to each other.

FIG. 2 shows another embodiment of the invention and like numerals have been used for like parts. Generally the support member 22 of FIG. 2 includes a core or rod 44 which extends through both portions24 and 26 of this member for reinforcement purposes. A pair of like flat spring contacts 46 are embedded within the portion 26 and one end of each projects outwardly through the base 38'for electricalconnection to oneside of the source of power. The other ends 48 of the contacts 46 are slightly bent radially inwardly of the member 22 or laterally of the contacts Upon relative movement of the members 18 and 42, the sharpened edge 20 of the tube l2 engages the juncture between the ends 48 of the contacts and the contact bodies to close the circuit.

The inwardly bent ends 48 of the contacts provide for ease of telescopic movement of the member 12 over the contacts 46 in the same manner that the shoulder 34 provides for ease of movement of the member 12 of the FIG. 1 embodiment into engagement with the portion 32 of member 28.

Thus, this invention provides an improved switch.

We claim:

1. In combination with a pair of relatively movable members and a source of power, a switch comprising, in combination, first contact means secured to one of the relatively movable members and having an annular hollow free end portion, contact support means secured to the other relatively movable member and including a first annular guide portion telescopically receiving and piloting the free end portion of the first contact means, and a second portion, second contact means mounted on the second portion and located in the path of movement of the free end portion of the first contact means, the second portion including at least an exterior layer of shearable material covering the second contact means, relative movement of the relatively movable members forcing the free end portion of the first contact means to shear the exterior layer of the second portion and electrically contact the second contact means, and means connecting the first and second contact means across the source ofpower.

2. In combination with a pair of relatively movable members and a source of power, a switch comprising, in combination, first contact means secured to one of the relatively movable members and having an annular hollow free end portion provided with a sharpened edge, contact support means of shearable insulating material secured to the other relatively movable member and including first and second annular portions, the first annular portion telescopically receiving and piloting the free end portion of the first contact means, the second annular portion being of larger size than the first portion, second contact means embedded within the second portion under an exterior layer thereof and located in the path of telescopic movement of the free end portion of the first contact means, relative movement of the relatively movable members forcing the sharpened edge of the free end portion to shear off the exterior layer of the second portion and electrically contact the second contact means, and means connecting the first and second contact means across the source of power.

3. In combination with a pair of relatively movable members and a source of power, a switch comprising, in combination, first contact means secured to one of the relatively movable members and having an annular hollow free end portion provided with a sharpened edge, contact support means of shearable insulating material secured to the other relatively movable member and including first and second annular portions provided with a reinforcing core, the first annular portion telescopically receiving and piloting the free end portion of the first contact means, the second annular portion being of larger cross-sectional size than the first portion, the core including a portion under an exterior layer of shearable material providing second contact means located in the path of telescopic movement of the free end portion of the first contact means, relative telescopic movement of the relatively movable members forcing the sharpened edge to shear the exterior layer of the second contact means and electrically contact the second contact means, and means connecting the first and second contact means across the source of power.

4. In combination with a pair of relatively movable members and asource of power, a switch comprising, in combination a hollow annular tube secured to one of the relatively movable members and having one free end thereof provided with a sharpened edge, a member of-shearable insulatingmaterial secured to the other relatively movable member and including a first annular guide portion telescopically receiving and piloting the free end of the tube and a second annular portion of larger cross-sectional size than the first portion, second conend of the tube, relative movement of the first and second relatively movable members forcing the sharpened edge to shear the exterior layer of the second portion and electrically tact means embedded within the first and second portions and 5 Contact the Second Contact means and means connecting the including a portion under an exterior layer of the second portion located in the path of telescopic movement of the free tube and second contact means across the source of power. 

1. In combination with a pair of relatively movable members and a source of power, a switch comprising, in combination, first contact means secured to one of the relatively movable members and having an annular hollow free end portion, contact support means secured to the other relatively movable member and including a first annular guide portion telescopically receiving and piloting the free end portion of the first contact means, and a second portion, second contact means mounted on the second portion and located in the path of movement of the free end portion of the first contact means, the second portion including at least an exterior layer of shearable material covering the second contact means, relative movement of the relatively movable members forcing the free end portion of the first contact means to shear the exterior layer of the second portion and electrically contact the second contact means, and means connecting the first and second contact means across the source of power.
 2. In combination with a pair of relatively movable members and a source of power, a switch comprising, in combination, first contact means secured to one of the relatively movable members and having an annular hollow free end portion provided with a sharpened edge, contact support means of shearable insulating material secured to the other relatively movable member and including first and second annular portions, the first annular portion telescopically receiving and piloting the free end portion of the first contact means, thE second annular portion being of larger size than the first portion, second contact means embedded within the second portion under an exterior layer thereof and located in the path of telescopic movement of the free end portion of the first contact means, relative movement of the relatively movable members forcing the sharpened edge of the free end portion to shear off the exterior layer of the second portion and electrically contact the second contact means, and means connecting the first and second contact means across the source of power.
 3. In combination with a pair of relatively movable members and a source of power, a switch comprising, in combination, first contact means secured to one of the relatively movable members and having an annular hollow free end portion provided with a sharpened edge, contact support means of shearable insulating material secured to the other relatively movable member and including first and second annular portions provided with a reinforcing core, the first annular portion telescopically receiving and piloting the free end portion of the first contact means, the second annular portion being of larger cross-sectional size than the first portion, the core including a portion under an exterior layer of shearable material providing second contact means located in the path of telescopic movement of the free end portion of the first contact means, relative telescopic movement of the relatively movable members forcing the sharpened edge to shear the exterior layer of the second contact means and electrically contact the second contact means, and means connecting the first and second contact means across the source of power.
 4. In combination with a pair of relatively movable members and a source of power, a switch comprising, in combination , a hollow annular tube secured to one of the relatively movable members and having one free end thereof provided with a sharpened edge, a member of shearable insulating material secured to the other relatively movable member and including a first annular guide portion telescopically receiving and piloting the free end of the tube and a second annular portion of larger cross-sectional size than the first portion, second contact means embedded within the first and second portions and including a portion under an exterior layer of the second portion located in the path of telescopic movement of the free end of the tube, relative movement of the first and second relatively movable members forcing the sharpened edge to shear the exterior layer of the second portion and electrically contact the second contact means, and means connecting the tube and second contact means across the source of power. 